Heater and a control system for a heater

ABSTRACT

A heater is provided which has a heating chamber divided into a plurality of heating compartments, each operably to provide heat in a respective heating direction. The heater includes a respective heating element for each heating compartment, and the operation of at least one of the heating elements is independently controllable from the operation of at least one other heating element. There is also provided a gas burner assembly the heat and a control system controlling the operation of the heating element.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to AU Provisional Patent Application No. 2016903166, filed Aug. 11, 2016, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to heaters, and more particularly, but not exclusively, to outdoor gas fired radiant heaters, which are often referred to as Patio Heaters. The invention also relates to a control system for a heater.

BACKGROUND TO THE INVENTION

Existing gas fired radiant heaters include upright heaters with a chamber to store a gas bottle at the bottom and a heater module at the top. The chamber and the heater module are connected by a pole or similar structure. The assembled heater can have a height of about 2100 mm. Generally there is provided an umbrella-like reflector covering the upper heater module.

There are shorter variations of this type of heater.

Almost all of these types of heaters have a burner at the top with a flat or pancake type burner burning inside a mesh walled cylindrical combustion chamber. This chamber generally has a solid top and a perforated bottom to allow ingress of secondary combustion air.

Generally beneath the combustion chamber is a nacelle housing the requisite gas valves and flame management hardware.

A prior art heater is described with reference to FIG. 1. A gas bottle chamber (1) is provided at the bottom of the unit. Attached to the gas bottle chamber (1) is a pole or the like (2) supporting a top burner/combustion chamber unit (3). At the juncture of the pole (2) and the chamber (3) is generally provided a nacelle (4) housing the burner controls and control hardware (14).

The combustion chamber has perforated mesh walls (5) which allow hot flue gases to escape in a controlled manner. The flue gases are generated by the combustion of gas at a burner (6) which provides primary air and gas to the flames adjacent to each port (7) of the burner. The burner (6) is made up of a burner body (12) and a mixing tube/injector assembly (13). The mixing tube (13) mixes gas and air for the burner (6).

In operation, the burner (6) is provided, via the mixing tube (13), with gas from the gas bottle or other gas supply at the bottom of the unit. The burner controls and control hardware (14) present a correct mixture of gas and air for primary combustion to the burner ports (7).

The burner (6) is ignited by ignition hardware of the burner controls (14). Once alight and the flame is verified, secondary air for completion of the combustion process is urged by the action of the gas hardware and thermal forces, into the lower part of the combustion chamber via air inlets (8) so that a continuous clean combustion process is sustained within the cylindrical and basically vacant combustion chamber interior.

The hot flue gases are distributed over the inside of the mesh walls (5) by the restrictive nature of the mesh to the escaping hot gas, the hole to solid ratio (open area) being selected for that function.

The mesh walls (5), heated by the hot gas generally glow cherry red when in use, especially on high gas settings. The mesh walls (5) generally glow more at the top than the bottom, driven by the fact that the mesh is generally all one whole size and convection forces pool the hot gases more at the top.

A reflective cover (9) is normally provided to reflect ‘lost’ radiation that would otherwise radiate upwards and away from the intended target which is normally seated people.

It has been found that the unit depicted in FIG. 1 has some shortcomings.

The unit has a 360 angular degree radiation zone. In a lot of cases, the user may not wish to have radiation from say the back half of the burner, or may wish to have a lower setting for that hemisphere. For example, in that hemisphere, there may be no persons, or a wall or other object that does not need, or cannot withstand, heating (e.g. a pot plant, shrub, hose wall etc.). In addition, the use of gas for heating an unwanted target area is costly and environmentally not responsible.

It has also been found that the burner/combustion chamber design is inefficient in that being an open chamber inside, there is not directional control over the hot flue gases, so they tend to escape wherever restriction is the least, like on the downwind side of the mesh (3, 5). The lack of control over the hot gases indicates that the process may be inefficient as in most gas appliances control of the gases and secondary air is important. This lack of control also wastes gas.

It has also been found that the top surface of the combustion chamber, generally a non-perforated metal flat dish shape, gets very hot due to the uncontrolled flue gases as described above. This high surface area of hot metal radiates heat substantially vertically, relying on the umbrella reflector (9). This is substantially lost heat, again adding to the running cost/task efficiency of the unit.

SUMMARY OF THE INVENTION

The present invention seeks to overcome at least some of the shortcomings identified above and/or to at least provide the public with a useful choice.

In one aspect, the present invention provides a heater comprising:

heating means for heating gas in at least one heating chamber; wherein the at least one heating chamber comprises a plurality of heating compartments each being operable in a heating operation to provide heat in a respective heating direction, wherein the heating direction of each heating compartment is different from the heating direction of the at least one other heating compartment, and wherein the heating means comprises a respective heating element for each heating compartment, the heating operation of at least one of the heating elements being independently controllable of the heating operation of at least one other of the heating elements.

The heater preferably includes a control system for controlling the heating operation of the heating elements.

Preferably the control system includes a separate control for each heating element of the heating means. This enables the operation of at least one of the heating elements to be independently controllable from at least one other of the heating elements.

In one preferred embodiment, the at least one heating chamber is provided in a housing having one or more internal partitions which divide the housing into the plurality of heating compartments.

In a preferred embodiment, the heating elements are gas burners.

In an alternative embodiment, the heating elements could conceivably be electric heating elements for heating air in each heating compartment. In this case, the control system may include separate electric controls, e.g. in the form of switches, for independently controlling the operation of each heating element.

The heating elements of the heating means preferably include at least one gas burner for each heating compartment.

In one preferred embodiment, a single burner assembly is provided which includes at least one gas burner for each heating compartment.

The burner assembly may include a plurality of mixing tubes, and a separate mixing tube is preferably provided for the burner in each heating compartment.

The heater preferably includes gas supply, with the control system controlling the flow of gas to the gas burners from the gas supply.

The control system preferably includes at least one valve for controlling the flow of gas from the gas supply to the gas burners.

The single assembly may comprise a burner plate having a plurality of flame outlets, a first combustion compartment connected to a first set of said plurality of flame outlets to form a first burner, and a second combustion chamber connected to a second set of combustion outlets to form a second burner, a first mixing tube connected to the first combustion chamber for supplying combustion gas to the first combustion chamber, and a second mixing tube connected to the second combustion chamber for supplying a combustion gas to the second combustion chamber.

According to a second aspect of the invention, there is provided a gas burner assembly for a heater comprising a burner plate having a plurality of flame outlets, a first combustion compartment connected to a first set of said plurality of flame outlets to form a first burner, and a second combustion chamber connected to a second set of combustion outlets to form a second burner, a first mixing tube connected to the first combustion chamber for supplying combustion gas to the first combustion chamber, and a second mixing tube connected to the second combustion chamber for supplying a combustion gas to the second combustion chamber.

Preferably, the flame outlets are of tubular form and arranged around the periphery of the burner plate.

The assembled burner may include a top burner plate and a bottom burner plate, connected together, each having a plurality of part tubular sections around its periphery.

In one embodiment, the top burner plate has two semi-circular raised walls on either side of a diameter of the burner plate and the bottom burner plate has two semi-circular recessed walls on either side of said diameter, wherein in the assembled burner, the semi-circular raised walls and the semi-circular recessed walls together form the first and second combustion chambers of the burner assembly.

The control system may include a plurality of valves, each valve controlling the flow of gas to a respective gas burner.

The control system preferably includes at least one ignition for igniting the gas supplied to at least one of the gas burners.

In one embodiment, the control system includes a plurality of ignitions, each ignition being independently controllable to ignite the gas supplied to a respective gas burner.

In an alternative, preferred embodiment, the control system comprises a master-slave control system which has a separate control for controlling each valve of the plurality of valves, and a single ignition for igniting the gas supplied to a first gas burner via a first valve, wherein gas supplied to the other gas burners via other valves of the plurality of valves is ignited by a cross-lighting effect from the flames of the first burner.

The heating chamber is preferably at least partly defined by at least one mesh wall and includes at least one baffle or reflector inside the heating chamber to guide the heated gases towards the at least one mesh wall of the heating chamber.

In one embodiment, the at least one baffle or reflector may be parallel to the at least one mesh wall of the heater.

In a more preferred embodiment, the at least one baffle or reflector approaches the at least one mesh wall at an angle. Preferably, the at least one baffle or reflector extends from a lower end positioned inwardly of the at least one mesh wall to an upper end positioned adjacent to the at least one mesh wall.

The at least one baffle or reflector preferably includes a high insulation material. The at least one baffle may be formed from the high insulation material, or alternatively, the high insulation material may be provided on a surface of the at least one baffle or reflector.

According to another aspect of the invention, there is provided a control system for a heater the heater comprising at least one heating chamber having a plurality of heating compartments, and a plurality of heating elements which includes a respective heating element for each heating compartment, wherein the control system controls a heating operation of each heating element, the control system including:

a main control for controlling the operation of at least one of the heating elements; at least one secondary control for selectively controlling the operation of at least one other of the heating elements.

Preferably, the heating elements are gas burners. The main control may control the supply of gas to a first gas burner for heating gas in one of the heating compartments, with the control system including an ignition for igniting the gas supplied to the first gas burner.

Preferably, the secondary control independently controls the supply of gas to at least one secondary gas burner for heating gas in another of the heating compartments.

In one embodiment, the secondary control may include at least one other ignition for igniting the at least one secondary gas burner for heating gas in said other heating compartments.

In an alternative embodiment, the at least one other ignition may be omitted and the arrangement is preferably such that when the gas supplied to the first gas burner is ignited, the secondary control(s) is selectively operable to supply gas to the at least one secondary gas burner, the gas supplied to said at least one secondary gas burner being ignited from the ignited gas from the first gas burner. In this case, the secondary control may include a gas cock.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described, by way of non-limiting example, with reference to the accompanying drawings in which:

FIG. 1 shows a prior art heater;

FIG. 2 shows a sectional side view of a heater according to an embodiment of the present invention;

FIG. 3 shows a sectional side view of a heater according to an alternative embodiment of the present invention;

FIG. 4 shows a top view of the heating chamber of FIG. 3;

FIG. 5 shows an exploded perspective view of a heater according to a further embodiment;

FIG. 6 shows a perspective view of the gas burner assembly of the heater of FIG. 5;

FIG. 7A is a side view of a first burner plate of the gas burner of FIG. 6;

FIG. 7B is a top plan view of the first burner plate of FIG. 7A;

FIG. 7C is a cross-sectional view of the burner plate of FIG. 7A;

FIG. 8A is a side view of a second burner plate of the gas burner of FIG. 6;

FIG. 8B is a top plan view of the second burner plate of FIG. 8A;

FIG. 8C is a cross-sectional side view of the burner plate of FIG. 8A.

DESCRIPTION OF PREFERRED EMBODIMENT

Referring to FIG. 2, a heater (20) according to an embodiment of the present invention comprises heating means (11) for heating gas in a heating chamber (22). The heating chamber (22) is of similar form to the heating chamber (3) of the heater of FIG. 1 in that it is defined by a top surface (24), mesh side walls (25) and a lower wall (26) provided with air inlets (28). The heating chamber (22) differs from that of the heater of FIG. 1 in that it is divided by at least one partition (10) into two or more heating compartments (23). The heating means (11) comprises a plurality of heating elements (21), preferably in the form of gas burner elements (21) which may form part of a burner assembly (11). A respective heating element (21) is provided for each heating compartment (23).

FIG. 2 shows a twin compartment heating chamber in the form of a divided combustion chamber (22), though it will be appreciated that a plurality of partitions may divide the heating chamber into more than two heating compartments. The partition (10) is provided to substantially separate heated flue gases from the gas burner (21) on one half of the burner assembly (11) from the other gas burner (21). In this way, flue gases from the heating compartment (23) on one half of the combustion chamber (22) cannot heat the mesh walls (25) of the opposite half of the combustion chamber (22). Thus a separate gas burner (21) is provided for each half of the divided combustion chamber (3). The heating means may be two separate gas burners, but the preferred embodiment includes a pair of gas burners (21) integrated into a single heating assembly (11). This burner assembly (11) is also characterized by having a plurality of mixing tubes (33). In this case we refer to two mixing tubes (33) for clarity. These mixing tubes (33) are respectively mounted to each half or segment of the burner assembly (11) as shown. The burner assembly (11) may be divided internally into as many gas burner elements or segments as there are heating compartments with respective mixing tubes for each gas burner. In this case, a gas injector is included as part of each mixing tube (33).

As well, in the preferred embodiments, there is provided a novel control mechanism. In one embodiment, there may be provided two or more independently controllable complete gas controls (34), with respective ignition hardware for each gas burner element or segment (21), and this arrangement is shown in FIG. 3. It has, however, been found that this arrangement would be costly and inconvenient, and that a novel control mechanism can be successfully utilised in the preferred embodiment of the invention shown in FIG. 2. This is characterised by utilising a single Master gas control (44), with a single ignition mechanism and flame proving hardware, and a slave gas control (45) which is preferably in the form of a gas cock.

In this embodiment, the main gas control (44) ignites the first gas burner element or segment of the divided burner assembly (11). When the flame of the first burner element or segment is present and verified by the controller, only the first burner element or segment will be alight. The second (and any subsequent) burner element or segment can then be supplied with gas via the secondary slave gas control or gas cock (45). The second (and any subsequent) burner element or segment can be ignited by a cross lighting effect from the ignited gas from the first burner element or segment and the dividing wall (10) is preferably detailed to allow/enhance this cross lighting. The slave gas cock (45) is only supplied from the main gas control (44) so that the gas cock and second burner element or segment is indirectly controlled by the flame management system of the master control (44). This makes it more economically viable to have to or more separate heating elements or segments in the burner assembly (11) and combustion chamber (22).

It is also preferable to include control of hot flue gas within the compartments (23) of the heating combustion chamber (22) for efficiency and lower running costs.

In FIGS. 3 and 4 a heating combustion chamber (22) divided into two heating compartments (23) by a partition (10) is shown in section and top plan view. Inside this chamber there is provided at least one baffle/reflector (17) provided to guide the flue gases towards the open mesh walls (25). The baffle may be parallel with the mesh walls (25) but as shown in FIG. 3, it is preferred that the baffle or reflector (17) approaches the mesh walls (25) at an angle. Preferably, the baffle or reflector (17) extends from a lower position positioned inwardly of the mesh walls (25) where the flue gases are more voluminous to an upper end positioned adjacent to the mesh walls (25), where the flue gases are less voluminous. The wider part at the bottom (40) of the combustion chamber (22) is to ensure that there is enough volume/space for combustion to take place without the flames touching the walls, and the narrower part (41) at the top of the combustion chamber (22) minimizes exposure of the top surface (24) of the combustion chamber to heat.

The baffle (17) may further be enhanced by including a high temperature insulation material. The high temperature insulation material may be provided on the outer or inner surface of the baffle (17) to prevent heat loss from anywhere but the mesh walls. It has been found that the angled baffle (17) works better than a parallel baffle due to the squeezing effect on the flue gases as they rise and escape. The mesh walls (25) may also have a graded open area to balance out the flue gas heat exchange and escape of the flue gases to further enhance the efficiency of the unit.

FIGS. 5 to 8 show components of another embodiment of a heater (100). As shown in FIG. 5, a heater chamber is defined within a housing (110) having a cylindrical side wall (125) and a top wall (124). A lower wall member (112) is attachable to the side wall (125). The lower wall member (112) is of frustoconical form having an upper annular side wall (116), a tapered side wall (117) extending downwardly from the upper annular wall (116) and a lower annular side wall (118). In the assembled heater, the upper annular side wall (116) is attached to the lower part of the side wall (125) by fixing means, such as screws, bolts or the like. The lower annular side wall (118) can be attached to a nacelle housing (not shown) at the upper and of a pole (2) in similar manner to FIG. 1. The tapered side wall (117) has a plurality of openings (119) which allow the ingress of air into the lower part of the heater chamber.

The mixing tubes (133 a, 133 b) are arranged to be mounted to the lower annular side wall (118) of the lower wall member (112) by a mounting plate (114). In the assembled heater, the lower ends of the mixing tubes (133 a, 133 b) are connected to a gas supply (not shown). The upper ends of the mixing tubes (133 a, 133 b) are connected to the second, lower burner plate (122 b).

The heater (100) includes a gas burner (122) having a first, upper burner plate (122 a) and a second, lower burner plate (122 b), which are engageable with each other to form an assembled gas burner plate (described in further detail with reference to FIGS. 6 to 8). The heater (100) also includes mixing tubes (133 a, 133 b) for supplying gas to the gas burner. The heater (100) further includes a partition (111) for separating the heating within the housing (110) into two heating compartments.

FIG. 6 shows the gas burner (122) formed by the engagement of the first burner plate (122 a) and the second burner plate (122 b). The first burner plate (122 a) forms a top plate of the gas burner (122), while the second burner plate (122 b) forms a bottom plate of the gas burner (122). The gas burner (122) defines two combustion compartments (123 a, 123 b). Each compartment (123 a, 123 b) is in fluid communication with a respective one of the mixing tubes (133 a, 133 b) and combustion gas is directed into each combustion compartment (123 a, 123 b) through the respective mixing tubes (133 a, 133 b).

The gas burner (122) has a plurality of tubular flame outlets (124) formed by part tubular sections (124 a) of the first burner plate (122 a), which mate with part tubular sections (124 b) of the second burner plate (122 b) in the assembled gas burner (122). The tubular flame outlets (124) on one half of the gas burner (122) are connected to one of the combustion compartments (123 a), and the tubular flame outlets (124) on the half of the gas burner (122) are connected to the other one of the combustion compartments (123 b).

The part tubular sections (124 a, 124 b) are distributed along the circumference of the first and second burner plates (122 a, 122 b) respectively. The part tubular sections (124 a, 124 b) of each burner plate (122 a, 122 b) have a thickness of about 2 mm to 5 mm, preferably about 3 mm. The part tubular sections (124 a, 124 b) preferably have a length of about 30 mm to 60 mm, preferably between about 40 mm to 50 mm, and even more preferably about 45 mm.

Referring now to FIGS. 7A to 7C, the first burner plate (122 a) is provided with two semi-circular raised walls (126), each defining a top wall of a respective one of the combustion compartments (123 a, 123 b). The part tubular sections (124 a) are distributed along the circumference of the plate (122 a) except along the diameter of the plate between the two semi-circular raised walls (126) that divides the plate (122 a) into two burner halves (126). As shown in FIG. 7C, the combustion compartments (123 a, 123 b) are connected to the part tubular sections (124 a) such that, when the first burner plate (122 a) engages the second burner plate (122 b) to form the gas burner, combustion gas in the combustion compartments (123 a, 123 b) can flow towards flame outlets formed by the part tubular sections (124 a, 124 b) of the first and second burner plates (122 a, 122 b). The first burner plate (122 a) may have a diameter D1 of between about 180 mm and 220 mm, and preferably about 200 mm. A diameter D2 of the first burner plate (122 a), excluding the part tubular sections (124), is between about 140 mm and 170 mm, and preferably about 150 mm. In addition, the combustion compartments (123 a, 123 b) are separated from each other by a distance D3 of about 5 mm to 20 mm, and preferably about 8 mm to 15 mm. In addition, neighboring walls (126 a) of the combustion compartments (123 a, 123 b) are tapered away from each other such that the neighboring walls (126 a) form an angle R1 of between about 30° and 50°, and preferably about 40°, between the walls (126 a). The lower parts of the combustion compartments shown in FIG. 7C may have a depth D4 of about 5 mm to 15 mm, and preferably about 10 mm.

Referring now to FIGS. 8A to 8C, the second burner plate (122 b) is provided with two semi-circular recessed walls (128), each defining a bottom wall of a respective one of the combustion compartments (123 a, 123 b). The part tubular sections (124 b) are distributed along the circumference of the plate (122 b) except along the diameter of the plate that divides the plate (122 b) into the two recesses (128). As shown in FIG. 8C, the recessed walls (128) are connected to the part tubular sections (124 b) such that, when the second burner plate (122 b) engages the first burner plate (122 a) to form the gas burner, combustion gas in the combustion compartments can flow towards flame outlets formed by the part tubular sections (123 a, 123 b) of the first and second burner plates. The dimensions of the second burner plate (122 b) are generally similar to the dimensions of the first burner plate (122 a). The second heating plate (122 b) may have a diameter d1 of between about 180 mm and 220 mm, and preferably about 200 mm. A diameter d2 of the first heating plate (122 b), excluding the part tubular sections (124 b), is between about 140 mm and 170 mm, and preferably about 150 mm. The combustion compartments (123 a, 123 b) are separated from each other by a distance d3 of about 5 mm to 20 mm, and preferably about 8 mm to 15 mm. In addition, neighboring walls (128 a) of the combustion compartments (123 a, 123 b) are tapered away from each other such that the neighboring walls (128 a) form an angle r1 of between about 30° and 50°, and preferably about 40°, between the walls (128 a). The combustion compartments (123 a, 123 b) may have a depth d4 of about 5 mm to 15 mm, and preferably about 10 mm. Each lower part of the combustion compartments shown in FIG. 8c recessed wall (128) is additionally provided with an aperture (129) for receiving a respective one of mixing tubes. The centres of the apertures (129) may be spaced apart from each other by a distance d5 of about 60 mm to 70 mm, and preferably about 65 mm.

When the first burner plate (122 a) is assembled with the second burner plate (122 b), the semi-circular raised and recessed walls (126, 128) of the first and second burner plates form top and bottom walls of the respective heating compartments (123 a, 123 b) of the heating combustion chamber, where combustion gas is selectively communicated into each combustion compartment via the mixing tubes (134). The tapered neighboring walls (126 a, 128 a) in the first and second burner plates (122 a, 122 b) assist in directing the gas towards the flame outlets formed by the part tubular sections (124 a, 124 b) of the first and second burner plates (122 a, 122 b).

Various features of the different embodiments described with reference to the drawings may be combined into further embodiments. For example, the Master/Slave gas control arrangement (44, 45) of the embodiment of FIG. 2 could replace the independently controllable separate gas controls (34) of FIG. 3, and vice versa. Either of these types of gas control arrangement could be used in the embodiment of FIGS. 5 to 8. Also, the baffle/reflector arrangement of FIGS. 3 and 4 could be incorporated into the embodiment of FIG. 2, and the embodiment of FIGS. 5 to 8.

It will also be appreciated that various modifications could be made to the preferred embodiments without departing from the scope or spirit of the invention. For instance, the present invention is equally applicable to other shapes of combustion chamber (e.g. square/triangular/rectangular) and other layouts. 

1. A heater comprising: heating means for heating gas in at least one heating chamber; wherein the at least one heating chamber comprises a plurality of heating compartments each being operable in a heating operation to provide heat in a respective heating direction, wherein the heating direction of each heating compartment is different from the heating direction of the one other heating compartment, and wherein the heating means comprises a respective heating element for each heating compartment, the heating operation of at least one of the heating elements being independently controllable of the heating operation of at least one other of the heating elements.
 2. A heater according to claim 1, wherein a control system is provided for controlling the heating operation of the heating elements, and wherein the control system includes a separate control for each heating element of the heating means.
 3. A heat according to claim 1, wherein the at least one heating chamber is provided in a housing having one or more internal partitions which divide the housing into the plurality of heating compartments.
 4. A heater according to claim 2 wherein the heating elements are gas burners, and wherein the heating elements of the heating means include at least one gas burner for each heating compartment.
 5. A heater according to claim 4, wherein a single burner assembly is provided which includes at least one gas burner for each heating compartment, the burner assembly preferably includes a plurality of mixing tubes, and wherein a separate mixing tube is provided for each heating compartment.
 6. A heater according to claim 5, wherein the single burner assembly comprises a burner plate having a plurality of flame outlets, a first combustion compartment connected to a first set of said plurality of flame outlets to form a first burner, and a second combustion chamber connected to a second set of combustion outlets to form a second burner, a first mixing tube connected to the first combustion chamber for supplying combustion gas to the first combustion chamber, and a second mixing tube connected to the second combustion chamber for supplying a combustion gas to the second combustion chamber.
 7. A heater according to claim 4, wherein the control system controls the flow of gas to the gas burners from a gas supply, and the control system includes a plurality of valves for controlling the flow of gas from the has supply to the gas burners, each valve controlling the flow of gas to a respective gas burner.
 8. A heating according to claim 7, wherein the control system includes at least one ignition for igniting the gas supplied to at least one of the gas burners, and wherein the control system includes a plurality of ignitions, each ignition being independently controllable to ignite the gas supplied to a respective gas burner.
 9. A heater according to claim 8, wherein the control system comprises a master-slave control system which has a separate control for controlling each valve of said plurality of valves, and a single ignition for igniting the gas supplied to a first gas burner via a first valve, wherein gas supplied to the other gas burners via other valves of said plurality of valves is ignited by a cross-lighting effect from the flames of the first burner.
 10. A heater according to claim 1, wherein the heating chamber is at least partly defined by at least one mesh wall and includes at least one baffle or reflector inside the heating chamber to guide the heated gases towards the at least one mesh wall of the heating chamber.
 11. A heating according to claim 10, wherein at least one baffle or reflector is parallel to the at least one mesh wall of the heater; or at least one baffle or reflector approaches the at least one mesh wall at an angle, and the at least one baffle or reflector extends from a lower end positioned inwardly of the at least one mesh wall to an upper end positioned adjacent to the mesh wall.
 12. A heating according to claim 10, wherein the least one baffle or reflector includes a high insulation material.
 13. A gas burner assembly for a heater comprising a burner plate having a plurality of flame outlets, a first combustion compartment connected to a first set of said plurality of flame outlets to form a first burner, and a second combustion chamber connected to a second set of combustion outlets to form a second burner, a first mixing tube connected to the first combustion chamber for supplying combustion gas to the first combustion chamber, and a second mixing tube connected to the second combustion chamber for supplying a combustion gas to the second combustion chamber.
 14. A gas burner assembly according to claim 13, wherein the flame outlets are of tubular form and arranged around the periphery of the burner plate, and wherein the assembled burner includes a top burner plate and a bottom burner plate, connected together, each having a plurality of part tubular sections around its periphery.
 15. A heater or burner assembly according to claim 14, wherein the top burner plate has two semi-circular raised walls on either side of a diameter of the burner plate and the bottom burner plate has two semi-circular recessed walls on either side of said diameter, wherein in the assembled burner, the semi-circular raised walls and the semi-circular recessed walls together form the first and second combustion chambers of the burner assembly.
 16. A control system for a heater wherein the heater comprises at least one heating chamber having a plurality of heating compartments, and a plurality of heating elements which includes a respective heating element for each heating compartment, wherein the control system controls a heating operation of each heating element, the control system including: a main control for controlling the operation of at least one of the heating elements; at least one secondary control for selectively controlling the operation of at least one other of the heating elements.
 17. A control system according to claim 16, wherein the heating elements are gas burners, the main control controlling the supply of gas to a first gas burner for heating gas in one of the heating compartments, wherein the main control includes an ignition for igniting the gas supplied to the first gas burner.
 18. A control system according to claim 17, wherein the secondary control independently controls the supply of gas to at least one secondary gas burner for heating gas in another of the heating compartments.
 19. A control system according to claim 18, wherein the secondary control includes at least one other ignition for igniting the at least one secondary gas burner for heating gas in said other heating compartments, or wherein when the gas supplied to the first gas burner is ignited, the secondary control(s) is selectively operable to supply gas to the at least one secondary gas burner, the gas supplied to said at least one secondary gas burner being ignited from the ignited gas from the first gas burner.
 20. A control system according to claim 16, wherein the secondary control includes a gas cock. 